Why do we bother with metric?

A recent question put to UKMA via its web site contact form is one that comes up frequently. Some may consider this surprising as the debate has been going on for at least fifty years. Are we missing something?

This is the question recently put to UKMA. The message read:

“Dear Metric supporters, why do you bother? My book is 22.86 cms high by 15.24 cms wide. Can you visualise it?
The imperial system grew up over decades and makes far more sense than metric. Base 12 is divisible by twice as many fractions as metric, making it much more flexible (two thirds of ten, anyone?).
Centimetres are too small, kilometres too short, there’s no equivalent to the handy ‘foot’ and the metre is just a yard that’s got above itself.
How much does a new-born baby weigh?
The metric system is inefficient, impractical and just plain dull. Again, why on earth (24,902 miles circumference) do you support it?
My book is nine inches high by six inches tall.”

Arguments like that expressed above have been aired in public before in those rarely occurring debates on the subject in the media, so the sender is not alone in that kind of thinking. It is doubtful that these views are typical but it probably does reflect a more widespread weakness in understanding measurement and the advantages of the metric system in particular.

The comments reveal more about a lack of familiarity and habitual use of metric units than the merits of the system.

Out of respect for the privacy of the sender, his/her identity will not be published. Answers to the points raised were given in a reply but we leave it up to readers’ comments to provide them here.

Author: UK Metric Association

Campaigning for a single, rational system of measurement

20 thoughts on “Why do we bother with metric?”

  1. Following the discussion on the Jeremy Vine programme on Radio 2 on 7 September, this article appeared on the BBC web site:

    The BBC tries to maintain a balance, and we should be thankful for this – it ensures the case for a single system of measures gets an airing, which rarely occurs elsewhere in the media. This BBC article and others before it refer to some of the views of the person who left the comment on the UKMA web site, but as we know there are none as deaf as those who don’t want to hear.


  2. Dear reader,

    How many gallons are contained in a cubic watertank whose side is 1 yard? The answer is not straightforward and will probably need to convert to metric first and then back to imperial:
    (1 yd)³ = ( 0.9144 m)³ = 0.76455485798 m³ = 0.76455485798 / 0.00454609 gal
    = 168.178 gal.
    Now, how many litres are contained in a cubic watertank whose side is 1 meter? Simple:
    1 m³ = (10 x 1 dm )³ = 1,000 dm³ or 1,000 L.

    For standalone measurements, any unit could fit, but as soon as you try to do something that involves having them interact, the US customary and Imperial systems show their deficiencies. Only the metric system provides a set of consistent units that can work together. Why do you think the construction industry rushed to metricate in the UK as soon as possible? Avoiding the conversion mess that the imperial system carried within itself was a very strong incentive. Why do you think physics use metric all the way?

    Also in most countries, people are taught metric only from day one. I was raised abroad, so as a matter of fact, I can perfectly visualise your 22.9 x 15.2 cm book, but I have no clue whatsoever about the dimensions of your 9 x 6 in book. “Visualising” is just a matter of familiarity, really. A new born baby weight is usually between 2.6 and 4 kg.

    By the way, here I used the decimeter (dm) a metric unit that is a tenth of a meter (so that’s could be your replacement for the “handy foot”). It’s not used very often even in metric countries, but it’s perfectly understood as they are also used to name ruler dimensions: http://online.abacus.coop/es/regle-de-doble-decimetre-faibo.html

    Best regards,



  3. Yes. Base 12 fractions would provide more even fractions, but as we count by tens, metric weights and measures fit better. But as for imperial weights and measures being natural, only today, one of my students asked me, “What’s 6 foot 2 mean?” Why? The boy came from China and these measures were quite foreign to him.

    When my son was going to go to the United States I tried to prepare him for it by explaining the relationship between Celsius and Fahrenheit temperatures. His eyes glazed over and he just couldn’t be bothered even hearing me out. It’s the same with weights. It’s all kilograms in Australia these days. No back conversions to stones and pounds. They went out in the 1970s. Distances are always in kilometres on the roads; bridge heights are always in metres. Yes, there are Imperial legacy units in a few places but for the most part it’s metric all the way, even for the oldies!

    Why? Because metric is all you need and it’s all that is used in most parts of the world for almost all uses.

    As metric measures came into Australia in the 1970s, you have to be well over 40 to have any memory of their use. In 20 years, those who remember the old units will mostly be dead and gone. And that also applies in New Zealand, South Africa, India and the rest of the Commonwealth. Britain and America will be left like shags on the rock. All the rest of the world will have moved on.


  4. What strikes me as both sad and perplexing is that the exact same arguments from the correspondent cited in this post could have been made to retain £sd at the time Westminster was proposing to decimalize Britsh currency.

    “The tradition British currency grew up over decades and makes far more sense than decimal currency. £sd are divisible by more fractions than decimal currency, making it much more flexible.

    New pence are too large and not as useful as old pence and shillings.

    Decimal currency is inefficient, impractical and just plain dull. Again, why on earth would one support it?”

    And as CharlieP@ might have added:

    “The ruthless stamping-out of such proud British culture and traditions is so unnecessary and would be grossly wasteful too.”

    Does anyone (including ardent opponents of metrication) believe that the decimalization of British currency was a mistake? Would they propose reviving £sd coins and notes to be used freely alongside the new coins with shopkeepers, real estate agents, etc permitted to post their prices in either system and to mix and match prices as they pleased?


  5. The sender was probably that rascal Warwick Cairns trying to seek attention.
    If someone described a book to me as nine inches high by six inches tall (sic) I would have a fair idea because it’s a small number of inches but I’d probably multiply 9″ by 25 and multiply 6″ by 25 in my head to visualise the approximate size in millimetres to be sure.
    As for the imperial non-system making more sense than metric: I think whoever sent it is taking a rise. 12 inches in a foot, 3 feet in a yard, 5280 feet (or is it foot?) or 1760 yards in a mile (a word derived from the Latin word for a thousand that isn’t a thousand of anything any more) does not appear to make any sense whatsoever to me. I haven’t even mentioned fluid ounces pints, gallons, quarts, pounds, stones and hundredweights. Far too nonsensical.
    As an architectural technician I work with numbers every day and the fact that base twelve is ‘divisible by twice as many fractions as decimal’ hasn’t hindered my work in any way. I might occasionally have to divide a dimension of (say 10m) into three parts and end up with two lengths of 3335mm and one of 3330mm. Or I just dimension it “equal, equal, equal”. I don’t lose sleep over the 5mm difference. Compared to adding up chains of dimensions in feet, inches and fractions it’s an insignificant problem.
    I use millimetres in my work more than centimetres but I don’t find either too short or long. They are what they are. I find it very easy to visualise a kilometre and divide it into blocks of 100 metres in my head. I don’t think there are many people in the world that even know how many feet or yards there are in a quarter or three quarters of a mile off the top of their head. I don’t. The American practice of subdividing miles into decimals of miles is even more confusing and giving altitudes in thousands of feet is a really ridiculous concept.
    I don’t make a habit of measuring things with my body-parts but I know a long stride is approximately a metre, the width of my palm is exactly 100mm and my foot is close to 300mm. I’m 175cm tall and weigh 90kg so I can judge things in comparison to my height and weight if the height or weight are given in the same units but if they’re given in feet, inches,pounds or stones I’m completely lost.
    How much does a new-born baby weigh? I have three children born in 1977, 1980 and 1985. They were all born in the same hospital in South West London. Their weights were all registered in kilograms and that’s what I remember. I don’t have any idea how many pounds and ounces they weighed because I don’t weigh anything in those units. Who does any more?
    Anyone with any sense, if they’re being honest, can see that it’s the imperial/US Customary method that is inefficient and impractical. As for being dull; Give me dull over stupidity any day.


  6. Why do we bother with metric units weights?

    Why do people use weights? One person might want to use weights to buy some cheese in order to make cheese soufflé. The quantity of cheese is stated in the recipe. Another person might want to compare prices of cheese between two different retailers. A third person might want to compare the price of cheese cut to order at the deli counter with pre-packed cheese. A cheese manufacturer might want to sell their cheese both home and abroad. As regards the latter, I have certainly seen Cathedral City Cheese on sale in Germany while today I bought a 250 g pre-packed piece of Camembert that was made in France and which had essential information in five different languages.

    If we are to use both metric and imperial units, which of the above people should we inconvenience? To help you decide, it is worthwhile remembering one of the sayings in the IT industry “bugs breed in the corners and congregate on the boundaries”. In the case of measurements, one of the boundaries is conversion between units. The simplest way to remove all problems associated with conversion is to kick one of the systems of units into touch.


  7. The argument that metric units are not easily divisible by 3 and 4 is a hoary old chestnut first considered by the best brains in France in 1790. They concluded that system of units of measurement and the units used in counting should both have the same radix. While a duodecimal system had many advantages, such as divisibility by 3 and 4, they argued that it was highly probable that the French population would not take to counting in 12s rather than 10s. They therefore chose the second-best solution, namely to design a measurement system that was decimal based and to leave the counting system unchanged.

    For more information, see pages 71/2 at http://www.eipiphiny.org/books/history-of-binary.pdf. Those who have access to JSTOR might also find the 1936 paper “Legendre and the French Reform of Weights and Measures” by C. Doris Hellman (http://www.jstor.org/stable/301613?seq=1#page_scan_tab_contents) interesting.


  8. I do wonder sometimes why we bother learning in school. I mean what is the point if this country wants to go backwards let it, just don’t complain when we loose trade and respect. Let’s trade with the world oh btw we won’t use the international system though. What a joke we have become.


  9. I take up the points in the message sent to UKMA:

    since when does anyone express the dimensions of a book to two decimal places, so why does the writer of this message do that?

    imperial is not ‘base 12’ – the only 12 in imperial is the number of inches to a foot; imperial uses bases of 3 (feet to a yard), 12 (inches to a foot), 14 (pounds in a stone), 16 (fluid ounces in an American pint), 20 (fluid ounces in a UK pint) and 1760 (yards in a mile). Not very easy to remember or indeed calculate with (I had to check the fluid ounce figures as I do not claim to know imperial that well);

    the writer claims that centimetres and kilometres too short: too short for what? They are exactly what they are. If I drive a certain distance, the number of kilometres is just what it is: how can the kilometres be ‘too short’. If I measure the length, say, of a wall in my house, it comes out at x.xx metres. Why are the centimetres too short? They are just what they are;

    the writer claims that metric is ‘dull’; well, I must say I don’t get particularly turned on by metric either. But then I don’t expect to. I just use it to measure or weigh. That is what a measuring system does. I don’t think it is there to provide entertainment or excitement.

    And the writer finishes by telling us his book is so many inches high by so many inches tall. I must say, I always thought high and tall were the same thing, so perhaps imperial does do strange things to the brain.


  10. One of the things that really grinds my gears is a statement like this:
    “My book is 22.86 cms high by 15.24 cms wide”

    Accuracy to 2 decimal places is notoriously difficult to measure, unless the commenter had some laser calipers I would guess that that they just used a conversion rate from inches. Which has given false accuracy.

    I would be very surprised if the book was in fact 9 inches by 6 inches if you were to measure to two decimal places accuracy.

    When converting between units, accuracy should not be given to more significant digits than the original units. So a 9 inches by 6 inches book can only be said to be 23cm X 15cm.


  11. “Why do we bother with metric?”

    We bother with metric because 95% of the world’s population bothers with metric. Any other reason, for or against, is irrelevant.


  12. This is a typical metric opposer diversion and distraction tactic meant to throw of metric supporters. One simple question needs to be put to those that pass this nonsense on.

    If any of these points were true, the whole world would being using imperial or USC and metric would have been abandoned long ago and forgotten. Instead the whole world abandoned traditional and imperial units and flocked to metric.

    I’m sure if this fact was presented to them, they would clam up and ignore you or change the subject.


  13. @derekp:

    Notice that the BBC could not resist having a dig at the `French’ metric system in its article, without any mention of UK and international involvement at BIPM. A charter obligation to at least pretend to be `balanced’ does not make them objective or impartial.

    Imperial is not a system, no matter how often supporters claim it should be considered as such. At best, it is an accumulation of half-remembered Roman, Anglo-Saxon and Viking (and maybe even some Norman [French]) occupation measurement conventions increasingly formalised after the dark ages. All truly `imposed by Europe’, of course…

    FWIW, I only understand the metric measurements in the quoted correspondent’s monologue—so cannot vouch for the other. But I generally ignore anything beyond a 3rd significant digit (unless toleranced thusly) and don’t much bother with centimetres (unless squared or cubed). As we have <a href="http://metricviews.org.uk/2016/07/imperial-holdouts-in-the-uk-in-2016/comment-page-1/#comment-52448"recently observed, metric is no less amenable to fractions, if you really want—and of which there are an infinite number. A nominal Earth circumference of 40 Mm is a lot easier to remember and do mental arithmetic on than all that barleycorn `excitement’. If only consumer-grade GPS receivers could be persuaded to display gradian positions (and bearings)…

    p.s. Is there a recording/ transcript of the Jeremy Vine discussion available to license fee payers (or everyone else) without proprietary BBC and Adobe software?


  14. I notice that your correspondent insists on an accuracy of 0.1 mm when measuring in the metric scale, but is quite happy to work with an accuracy 250 times lower when he quotes the size of the book in imperial. The book is about 230 x 150 mm. I think we can all visualise that quite easily. I find it difficult to visualise his inch measurements since I have made a point of not using those units since I left school 35 years ago. They just don’t come naturally to me.
    I can also tell him that a new-born baby weighs between 2.5 and 4.5 kg, with the average being somewhere around 3.5. Perhaps he could tell us the weight in a single imperial unit. Please don’t give me pounds and ounces because those are two different units and I can’t add them together without doing a conversion (is it 16 ounces, or is that pounds in a foot, I can’t quite remember).
    He should also be aware that cm does not need a plural “s”. I’m sure he is aware of this and is just trying to appear ignorant. If I made up an abbreviation for inches – let’s use “ichs”, would I expect anyone else to understand it?
    And what on earth has the circumference of the earth got to do with his argument? That distance can be quoted in any unit system you like – 87,653,106 cubits perhaps?


  15. I’d like to follow the remark in the article about lack of familiarity and habitual use of metric demonstrated by the person who sent the message.

    If you think about it that’s all the person is really saying. They are not used to it so its no good.

    The person doesn’t appreciate the advantages of the millimetre for example. It is a small unit but for fine measurements you can work in whole numbers whereas with inches you need fractions.

    In the end its not the size of the unit that matters so much as how easy it is to use for the required resolution.

    When books or other objects have sizes that are an exact number of units it is because they were designed to fit the system being used not because there is some natural conclusion as to how big they should be. Photographs frames for instance are sometimes sold as 8 inches by 10, but could just as easily be 20 cm by 25.

    Critics of the metric system usually demonstrate shallow thinking on the subject. If they are actively opposing it they often fall back popularity and freedom of choice rather than the mathematical merits.

    That brings up a separate argument but suffice to say here, if there is a case for change, it has to be made properly. Democracy isn’t just about freedom to choose, it is about being able to make balanced and informed choices – sadly lacking on June 23rd 2016!


  16. What if in the future say a few centuries we started asking about the metric system? One day that will seem outdated too maybe? Or we will still be using imperial in the U.K if the U.K is still around?


  17. The metric system may look ‘dull’, but its history is far from it. The meausrement of the meridian by Delambre and Mechain was frought with difficulties and danger, also because of political upheavals, it was done during the Terror. It is also true that during its development important British and US contributions have been made to it.


  18. @Lee kelly.

    Well, there is a scientific community keeping the SI up to date. Except for redefining Imperial (and equally US Customary) in terms of metric, there have been no Imperial improvements since 1824 (or Customary since around 1700 when the Queen Anne wine gallon and Winchester bushel were tweaked by Parliament).


  19. The British scientific community’s contribution to metrology was to improve the metric system. On the theoretical side the concept of coherent units was developed by Maxwell and Kelvin, the use of scientist’s names for units of measure was a British development while the international prototype metre and kilogram were “Made in England”. (The metre was retired in 1960, but the 127 years later, the kilogram is still in use). Furthermore, three of the last four directors of the BIPM have been British.

    Apart from scientific developments in the 1790’s, the French contribution has been on the political front, while the British politicians have been happy to sell their own scientists “down the river”.


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